More knock again

S

StonesKid

New member
Can someone tell me how a knock sensor works? I understand that is senses knock LOL. But I want to know why taping an alternator bracket would cause knock. I have done a full tune up and I still seem to be getting knock upwards of 9 degrees. I don’t hear any ping and this is driving me nuts. I also recently change the Tstat to a 180 and no luck there either. Any help would be greatly appreciated.

Thanks
Alexander
 
BigAl...

BigAl...

Member
I'll give it a try (no flames PLEASE!), first, the knock sensor is a microphone that listens for noises whenever the ign is on, obviously it is constantly hearing noises so the signal is sent to the esm (filter that has been calibrated by GM to determine if the noise is actual detonation) once the filter determines that the noise is knock it says "PSSSSS hey boss we got some bad shit happenen here" and the ECM says "gotcha covered" and it starts to pull timing, the more detonation there is the more timing the ECM will retard.

Second, By tapping on the alt bracket or the block you are simulating detonation, and testing the esm and the ecm. When you tap you should see KR on Datamaster or scanner.

As for you not hearing knock that is actually good because it means that your computer is catching it before you can actually here it, by the time you here knock it's been knocking for awhile(BAD BAD!!).

As far as your knock problem, list all of your mods and I'm sure some of the guys will jump in from here.

BigAl...
 
S

StonesKid

New member
OK Here goes

180 degree tstat
ATR Aux Intercooler with larger cooling pump
Bosch External Fuel Pump
Bosch Adj Fuel regulator
CAC Kit
Boost gauge
Conrad Cap and Rotor
KB Red Hot wires
Valve cover breather
K&N
3 bar Ultimate chip
3 bar map sensor

And a full recent tune up with a timing check.
 
J

JoeLutz

New member
StonesKid
I got almost the exact same mods you got and I'm getting the same knock. What base fuel pressure you running?
It seems like the more FP I run, the beter it runs. I'm up to arround 53-54 psi base and it still feels lean, but is beter than it was.
I also had an external pump, but ditched that crap. Just get a good Walbro 255 High Press intank pump and get rid of that external. It will save you some headache. I am going to try checking the timing advance with a timing light vs. what the datamaster is reading. (Winded V6's suggestion) mabey you should try that too.
 
S

StonesKid

New member
I am running about 50psi, I plan to get an internal walbro by the summer. As for the timing, I checked it with a timing light. I did not know it was possible to check it with the datamaster. How is it done?

Thanks for you input
 
J

JoeLutz

New member
You set the timing with the timing light and the brown wire unhooked. The Datamaster just tells you how much the ECM is trying to advance the timing. Look at your total advance values. You can get a timing light with a dial so that when it is running with the brown wire hooked up, you just turn the dial on the timing light and that brings the timing mark back to zero position. Read the dial and that tells you how much the timing is actually advanced. Then compare that number to the number given by datamaster for how much it should be advanced. They should be very close to the same. It may be helpful to bring your laptop outside so you can look at it at the same time you are looking at the timing light. Also, when you checked your base timing (wire unhooked) if it was off any, I would deffinitely get a piston stop to check for Top Dead Center. Your harmonic balancer could have slipped like mine did.
 
S

StonesKid

New member
I am running the CR42TS and running the Ultimate on T1 15psi.

_________________
2001 Silver Grand Prix GTP
2000 Red Corvette FRC
1993 White GMC Typhoon

<font size=-1>[ This Message was edited by: StonesKid on 2001-12-11 10:24 ]</font>
 
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